Ultrasonic cleaning device for fragile heat-sensitive articles

ABSTRACT

The described device includes a glass receptacle for the articles to be cleaned, e.g. soft contact lenses. A piezoelectric crystal is secured to the bottom of the receptacle. An annular heat sink, e.g. of aluminum, surrounds the receptacle. The circuitry for operating the crystal, and an automatic timer for turning off the device after completion of an established cleaning time are disposed in a housing upon which the receptacle is mounted. The receptacle is normally filled with a cleansing solution such as saline solution, and the articles to be cleaned may be placed in a foraminous container to permit their easy retrieval from the receptacle.

nited States Patent Cummins et a1.

ULTRASONIC CLEANING DEVICE FOR FRAGILE HEAT-SENSITIVE ARTICLES Inventors: Millard M. Cummins; Thomas E. Ilankins; Robert Best; Frederick Biesecker, all of Columbus, Ohio Assignee: Soniclens, Inc., Columbus, Ohio Filed: July 9, 1971 Appl. No.: 161,050

U.S. Cl. ..259/72, 134/1, 134/184, 259/1 R, 259/D1G. 44

Int. Cl ..B01f 11/02, B08b 11/02 Field of Search ..259/1 R, 72, DIG. 41, D16. 44; 134/1, 184

References Cited UNITED STATES PATENTS Toulmin ..259/72 3,352,311 11/1967 Murphy ..259/72 X FOREIGN PATENTS OR APPLICATIONS 819,160 10/1951 Germany ..259/DIG. 44

Primary Examiner-Robert W. Jenkins Assistant ExaminerPhi1ip R. Coe Att0rneyCushman, Darby & Cushman [57] ABSTRACT The described device includes a glass receptacle for the articles to be cleaned, e.g. soft contact lenses. A piezoelectric crystal is secured to the bottom of the receptacle. An annular heat sink, e.g. of aluminum, surrounds the receptacle. The circuitry for operating the crystal, and an automatic timer for turning off the device after completion of an established cleaning time are disposed in a housing upon which the receptacle is mounted. The receptacle is normally filled with a cleansing solution such as saline solution, and the articles to be cleaned may be placed in a foraminous container to permit their easy retrieval from the receptacle.

7 Claims, 2 Drawing Figures PATENTEUMAR-l 31915 7 0,402

-FIG. 1

PZT IZIOO- 4 W W INVENTORS MILL/m0 M. Cum/1W5 THOMAS E. Hmmuus RooERT bE'OT FREDERICK BIEsEQKER ULTRASONIC CLEANING DEVICE FOR FRAGILE HEAT-SENSITIVE ARTICLES BACKGROUND OF THE INVENTION Bourgeaux November 4, l952 Platzman 3,1 13,76l December 10, I963 Mettler 3,180,626 April 27, 1965 Mettler 3,191,913 June 29, i965 Carmichael 3,405,9l6 October 15, 1968 Cook 3,433,462 March 18, 1969 It should be apparent from the above that little, if anything, has been done previously to make the technology of ultrasonic cleaning'available for general consumption. That, in order to be successfully accomplished requires that the device be inexpensive relative to the cost of industrial cleaning machinery that is subject to cash-flow-producing depreciation, it must be easy to use correctly and difficult to use incorrectly for a broad market of potential users, it must be able to perform its assigned task, and it must not be ultimately harmful to mankind.

Soft contact lenses are beginning to be marketed in the United States. Unless some unforeseen development inhibits the growth of this market, in the coming years a sizeable segment of our population, and that of other countries, will be wearing soft contact lenses.

A discussion of the nature and technology of soft, porous contact lenses is found in the following U.S. Pat. Nos.

Suffice it to say here that those who prescribe such lenses recommend that they be kept submerged in a fluid when they are not being worn and that they be cleaned periodically to remove dirt, degenerating eye fluids and organisms which, for such fluids, are growth media. The lens material can act as a porous support for such media.

Currently, one supplier of soft contact lenses (Griffin Laboratories) recommends that they be wetted with a cleansing solution known by the trade name Flexal and rubbed gently between the thumb and forefinger, then rinsed with the same cleansing solution. (Water, alone, will allegedly damage this type of lense).

While this method has, so far, appeared to be generally satisfactory, it has its drawbacks: some users rip their lenses while cleaning them in this manner, and biological culture tests show that this method does not usually remove all growth media and living organisms from the lens.

Clearly, a more effective means and method for cleaning such lenses is needed, but it must meet the other qualifications set forth above if it is to be successful.

The present applicants believe they have found such a means and method.

SUMMARY OF THE INVENTION The described device includes a glass receptacle for the articles to be cleaned, e.g. soft contact lenses. A piezoelectric crystal is secured to the bottom of the receptacle. An annular heat sink, e.g. of aluminum, sur rounds the receptacle. The circuitry for operating the crystal, and an automatic timer for turning off the device after completion of an established cleaning time are disposed in a housing upon which the receptacle is mounted. The receptacle is normally filled with a cleansing solution such as saline solution, and the articles to be cleaned may be placed in a foraminous container to permit their easy retrieval from the receptacle.

A frequency range of 60-100 khz is preferred by the inventors for lens cleaning. The preferred container size is 15 ml., eg a Pyrex beaker. The crystal may be one of barium titanate or any other material capable of producing such waves. Flexal, or similar cleansing solutions which soft contact lens suppliers furnish or recommend for the storage and/or cleansing of soft contact lenses is the presently preferred cleansing solution, although saline solutions may be used provided they are freshly prepared, are aseptic, or contain an acceptable preservative. Currently, in the United States, FDA. approval 'is being sought for a saline solution containing a preservative. However, the Agency is taking a somewhat cautious approach to ensure safeguards (e.g. unique packaging) are adopted to prevent inadvertent use of such solutions intravenously, since the solution concentrations are similar or identical to those used intravenously in the treatment of eg burns and shock.

It is crucial to the cleaning of certain soft contact lenses that the temperature of the solution be kept from rising to C., as the lenses will deteriorate. The ultrasonic vibration activity results in heating of the cleaning solution. According to the principles of the invention, a heat sink provi ded about the container carries off a sufficient amount of generated heat at a sufficient rate to keep the temperature of the fluid below about 55C. for a cleaning period lasting up to about 2 hours. I

The principles of the invention will be further hereinafter discussed with reference to the drawing wherein a preferred embodiment is shown. The specifics illustrated in the drawing are intended to exemplify, rather than limit, aspects of the invention as defined in the claims.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a longitudinal, vertical cross-sectional view of a device constructed in accordance with the invention; and

FIG. 2 is a typical schematic diagram of the electronic components and circuitry of the device.

DETAILED DISCUSSION OF THE PRESENTLY PREFERRED EMBODIMENT OF THE INVENTION The ultrasonic cleaning device 10 for small articles such as soft contact lenses includes a housing 12 shown including a first portion 14 made of aluminum coated with an electrical insulator and providing the floor 16 and front 18 of the housing. A molded part 20, e.g. made of Noryl" plastic, provides the sides, rear and top wall 22 of the housing. The two housing parts are fastened together, e.g. with fasteners 24. The bottom wall is provided with a plurality of depending feet 26 made of resilient material to ensure quietness in operation of the device.

Within the housing there is received a conventional mechanical timer 30, whose setting knob 32 is disposed exteriorly of the housing. The timer is preferably one which can be set to run for a suitable time such as 2 hours during which the control knob will progressively return to an off position. Only while the timer 30 is running, a cam 34 thereof (FIG. 2) maintains a switch 36 in a closed condition, supplying power through the circuitry 38 to a piezoelectric crystal 40. As is apparent, the device may be plugged into a normal residential electrical outlet; the input to the crystal 40 is typically 80 k.c., 130 v., m.a. The circuitry may be adapted to produce a comparable input where the distributed electric power is different or to provide an altered input where a crystal having differing requirements is chosen. Neither adaptation need depart from the principles as disclosed herein. What is depicted is typical and presently preferred.

It should now be noticed that a small round opening 42 is formed in the top wall 22 of the housing, e.g. above the circuit board 44 which mounts the circuitry 38. The opening 42 is, in this example, L125 inches in diameter.

The cleansing receptacle 46 is preferably glass, and preferably made of laboratory glassware that can withstand heat shock and mechanical shock. A Pyrex beaker, ml. size, is very acceptable. The dimensions of such a beaker are about 28 mm., O.D.; about 40 mm. height and about 0.05 inch wall thickness.

The receptacle 46 is disposed in the opening 42 so that most (e.g. five-sixths) of the receptacle lies outside the housing, but the bottom wall 48 of the receptacle lies within the housing.

The piezoelectric crystal 40 is secured to the bottom of the receptacle exteriorly of the bottom wall 48, e.g. using an epoxy cement 50.

The device 10 essentially includes means for dissipating heat from the receptacle at a sufficient rate to keep the heat from building up to a sufficient temperature as to cook" the soft contact lens material (or similarly to destroy any other heat sensitive articles being cleaned). In the instance of the preferred embodiment, the heat dissipating function is carried out using a heat sink 52. This is shown having the form ofa finned tube made of a material from which heat is easily and readily radiated, e.g. aluminum or an alloy thereof. Other suitable materials are on the tongue-tips of engineers conversant with heat dissipation technology.

Using e.g. the same epoxy cement 50, the internal peripheral surface 54 of the heat sink is secured to the exterior peripheral surface 56 of the portion of the receptacle that protrudes out of of the housing 12. Similarly, the lower end of the heat sink is secured to the exterior of the housing 12 peripherally of the opening 42.

A cover 58 removably surmounts the upper ends of the receptacle and the heat sink. It is shown having locater tabs which depend slightly into the receptacle in slight engagement with the inner peripheral surface of the sidewall of the receptacle. The cover is of sufficient weight that it is kept in place by gravity during use of the device, although the device could be operated successfully with the cover off. In the latter instance, some fluid loss might occur.

Although the lenses could be placed directly in the cleaning solution S within the receptacle, it is recommended that they be cleaned while disposed in an openwork, i.e. foraminous container, typically one C made of molded plastic. Such a container is currently supplied with its soft contact lenses by one or more suppliers of soft contact lenses. The container C has two hinged doors 66, one on each side, each removably closing a compartment in which one lens may be placed. The compartments are marked clearly to make it difficult to place the wearer's left lens in the compartment marked for receipt of his right lens, and vice ver- The device 10 could be used to clean other heat sensitive articles, however, it is especially well suited to clean soft contact lenses. The way the receptacle, heat sink and the housing are put together minimizes the prospect that the device will be used improperly, or idly tampered with. The design allows the device 10 to be made so inexpensively and so durably that it has a good potential for being successfully mass marketed. All the user has to do is place his lenses in a familiar container, place the container in the receptacle, replace the cover and set the timer. At the conclusion of the cleaning, the cover may be removed, the container taken from the receptacle and the lenses retrieved from the container. Typically, the cleaning could be done when the lens wearer removed his lenses for the evening. The lens wearer could then retrieve his cleaned lenses from the device in the morning. To this extent, the device can double as a storage device for soft contact lenses.

The heat sink of the device as shown will prevent the temperature of the lenses from rising above about 5()55 C. when the ambient air temperature is up to 30C., i.e. will provide sufficient heat dissipation to keep the solutions temperature rise below about 20C. In order to accomplish this, we have found it important that the heat sink extent around and up the sidewall of the receptacle and that it remain outside the housing. The heat sink could be enclosed if the enclosure were ventilated with forced air, but such provisions would needlessly add to the expense of the device and thus detract from its mass marketability.

It should now be apparent that the ultrasonic cleaning device for fragile heat-sensitive articles as described hereinabove possesses each of the attributes set forth in the specification We claim:

1. An ultrasonic cleaning device for fragile, heat-sensitive articles, comprising:

a. a receptacle for cleansing fluid;

b. a piezoelectric crystal connected to said receptacle for imparting ultrasonic vibrations thereto;

c. means for exciting said crystal to produce ultrasonic vibrations on the order of 60 khz.; and

(1. heat sink means surrounding said receptacle and being capable of preventing temperature rise of said solution to about 20C. above ambient temperature and the temperature of said solution to a maximum of about 55C.;

said crystal and said exciting means being disposed within a housing and said heat sink means and most of said receptacle being disposed exteriorly of the housing, the heat sink means being a finned tube extending around the whole portion of the receptacle exposed outside the housing, the outside of the receptacle being secured to the inside of the finned tube and the bottom of the finned tube being secured to the top of the housing peripherally of means defining an opening in the housing; the portion of the receptacle which lies within the housing entering the housing through said opening; and the connection of the piezoelectric crystal to the exterior of the bottom of the receptacle being disposed within the housing.

2. The device of claim 1 wherein the receptacle is a 115 milliliter beaker composed of laboratory glass.

3. The device of claim 1 further including a timing device operatively connected to said means for exciting, and for terminating the excitation after the time period for which the timing device has been set has expired.

4. An ultrasonic cleaning device for fragile, heat-sensitive articles, comprising:

a. a receptacle for cleansing fluid;

b. a piezoelectric crystal connected to said receptacle for imparting ultrasonic vibrations thereto;

c. means for exciting said crystal to produce ultrasonic vibrations;

d. heat sink means surrounding said receptacle and being capable of preventing temperature rise of said solution to about 20C. above ambient temperature and the temperature of said solution to a maximum of about 55C.;

e. a timing device operatively connected to said means for exciting, and for terminating the excitation after the time period for which the timing device has been set has expired;

said timing device, said crystal and said exciting means being disposed within a housing and said heat sink means and most of'said receptaclebeing disposed exteriorly of said housing;

the receptacle being a 15 milliliter beaker composed of laboratory glass;

about five-sixths of the height of the beaker lying outside the housing and the heat sink consisting of a finned aluminum tube extending about the whole exposed portion of the beaker;

the outside of the beaker being secured to the inside of the finned tube and the bottom of the finned tube being secured to the top of the housing peripherally of means defining an opening in the housing; the portion of the receptacle which lies within the housing entering the housing through said opening.

5. The device of claim 4 wherein said crystal when excited by said means produces vibrations on the order of 60-- khz.

6. The device of claim 4 wherein the piezoelectric 7. The device of claim 1 wherein the receptacle is a beaker made of heat and shpck es istant glass. 

1. An ultrasonic cleaning device for fragile, heat-sensitive articles, comprising: a. a receptacle for cleansing fluid; b. a piezoelectric crystal connected to said receptacle for imparting ultrasonic vibrations thereto; c. means for exciting said crystal to produce ultrasonic vibrations on the order of 60 - 100 khz.; and d. heat sink means surrounding said receptacle and being capable of preventing temperature rise of said solution to about 20*C. above ambient temperature and the temperature of said solution to a maximum of about 55*C.; said crystal and said exciting means being disposed within a housing and said heat sink means and most of said receptacle being disposed exteriorly of the housing, the heat sink means being a finned tube extending around the whole portion of the receptacle exposed outside the housing, the outside of the receptacle being secured to the inside of the finned tube and the bottom of the finned tube being secured to the top of the housing peripherally of means defining an opening in the housing; the portion of the receptacle which lies within the housing entering the housing through said opening; and the connection of the piezoelectric crystal to the exterior of the bottom of the receptacle being disposed within the housing.
 2. The device of claim 1 wherein the receptacle is a 15 milliliter beaker composed of laboratory glass.
 3. The device of claim 1 further including a timing device operatively connected to said means for exciting, and for terminating the excitation after the time period for which the timing device has been set has expired.
 4. An ultrasonic cleaning device for fragile, heat-sensitive articles, comprising: a. a receptacle for cleansing fluid; b. a piezoelectric crystal connected to said receptacle for imparting ultrasonic vibrations thereto; c. means for exciting said crystal to produce ultrasonic vibrations; d. heat sink means surrounding said receptacle and being capable of preventing temperature rise of said solutioN to about 20*C. above ambient temperature and the temperature of said solution to a maximum of about 55*C.; e. a timing device operatively connected to said means for exciting, and for terminating the excitation after the time period for which the timing device has been set has expired; said timing device, said crystal and said exciting means being disposed within a housing and said heat sink means and most of said receptacle being disposed exteriorly of said housing; the receptacle being a 15 milliliter beaker composed of laboratory glass; about five-sixths of the height of the beaker lying outside the housing and the heat sink consisting of a finned aluminum tube extending about the whole exposed portion of the beaker; the outside of the beaker being secured to the inside of the finned tube and the bottom of the finned tube being secured to the top of the housing peripherally of means defining an opening in the housing; the portion of the receptacle which lies within the housing entering the housing through said opening.
 5. The device of claim 4 wherein said crystal when excited by said means produces vibrations on the order of 60-100 khz.
 6. The device of claim 4 wherein the piezoelectric crystal is connected to the exterior of the bottom of the beaker within the housing. 